The present invention concerns a grip roller overrunning clutch, e.g. for use in an automatic transmission.
Grip roller overrunning clutches typically have a first clutch part provided with grip ramps for the grip rollers, a second clutch part provided with a cylindrical running surface for the grip rollers, chamber-forming components holding the grip rollers and associated pressure springs loading the grip rollers in the gripping direction. The pressure springs are composed of band springs folded in the longitudinal direction and, in the assembled state, the folds extend in the radial direction.
In the known grip roller overrunning clutch constructions of this kind, the band springs are held between the rollers and chamber-forming components, e.g. a cage, without any substantial guide in the region of their contact with the grip rollers. During the overrunning operation, the springs, which attempt to push the grip rollers into the gripping position, are acted on discontinuously by the "shimmying, " i.e., the relatively undefined motion in the peripheral direction of the overrun, of the grip rollers so that at least the first two folds or corrugations of the band spring are dynamically loaded to a varying extent through the action of the grip rollers. At the same time transverse forces occur which cause the folds of the band spring that extend radially relative to the overrun, to butt against one or the other boundary wall of the chamber-forming components. The constant discontinuous action on the folds leads to constant friction between the folds and the lateral boundary walls, and thus to wear which, in the end, may lead to a breaking of the spring.